Theoretical Studies on Electronic Spin Flipping and Relevant Phenomena in Optoelectronics

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Theoretical Studies on Electronic Spin Flipping and Relevant Phenomena in Optoelectronics******Electrons have an intrinsic spin that can take two quantized values, just like the two faces of a coin. Flipping electronic spin can drastically change the reactivity of a molecule and lead to unexpected results. Electronic spin flipping occurs in many reactions involving oxygen, especially in the realms of biochemistry and combustion chemistry. For instance, it occurs in the oxidation reaction in breathing. We have all adapted to the spin-flipping rate that was chosen by nature. If suddenly the flipping of the oxygen electronic spin were slower, we would all have oxygen deprivation symptoms. If it were too fast, we would all start to burn and become the more stable carbon dioxide and water. Given the importance of electronic spin flipping in chemistry, we endeavor to develop accurate and efficient theoretical chemistry methods to simulate the flipping. Compared to other methods that have been developed, our methods will include the important nuclear quantum effects and will be more efficient, and hence more applicable to large, realistic systems. The methods will be applied to investigate interesting flipping processes and explain/predict phenomena.******Our research program has applications that are related to energy science and sustainable chemistry. We will not be able to rely on fossil fuel exclusively. Solar energy is a clean alternative, and certain types of organic materials can convert solar energy to electricity. Organic materials are attractive because they feature numerous advantages such as low cost, high production, and mechanical flexibility. However, organic solar cells are not as widely used today as their inorganic counterparts and one reason is their relatively low light-to-electricity conversion efficiency. We aim at designing organic molecules that can undergo intramolecular singlet fission, a process that can potentially double the conversion efficiency. Organic light-emitting diodes take the opposite process of organic solar cells. They convert electricity to light and feature similar advantages, but also low conversion efficiency. We will employ theoretical chemistry methods to design organic molecules that undergo thermally activated delayed fluorescence, a process that has been shown to significantly increase the energy conversion efficiency from ~5% to ~20%. We are especially interested in designing small molecules for organic solar cells and organic light-emitting diodes, since they are lightweight and will eventually lead to transportation-friendly devices.******This research program has a significant impact in making energy efficient devices. It will eventually benefit Canada's energy-related industry. It is a combination of theoretical development and applied studies, and therefore provides an opportunity for multidisciplinary personnel training.**